This invention relates to a scroll compressor wherein the main benefits of fixed throw and radially compliant compressors are both achieved.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor, a first scroll member has a base and a generally spiral wrap extending from the base. The second scroll member has a base and a generally spiral wrap extending from its base. The wraps of the two scroll members interfit to define compression chambers. The shaft is driven by an electric motor to rotate, and causes the orbiting scroll to orbit relative to the non-orbiting scroll. As the two orbit relative to each other, the size of the compression chambers decrease, and an entrapped refrigerant is compressed. The compression chambers are partially defined by contact between the flanks of the wraps of the two scroll members. In one type of scroll compressor, the position of the two wraps relative to each other is relatively fixed through the orbit. Such a scroll compressor is known as a xe2x80x9cfixed throwxe2x80x9d.
While a fixed throw compressor does have some benefits, it also has downsides. In particular, fixed throw scroll compressors are usually quieter than a second type of scroll compressor known as xe2x80x9cradially compliantxe2x80x9d. However, tolerance control in a fixed throw scroll may result in significant leakage gaps between the scroll flanks. Moreover, if there is ever an entrapped contaminant, a fixed throw scroll member does not have all of the benefits of a radially compliant scroll.
In a radially compliant scroll, the connection between the driveshaft and the orbiting scroll is a through a slider block such that the orbiting scroll can move or xe2x80x9cslidexe2x80x9d into and away from engagement from the non-orbiting scroll wrap. A centrifugal force forces the scroll wraps into contact. A force between the two wraps will tend to move the scroll members out of the contact at their flank surfaces. Due to the centrifugal force acting between the two, there is thus a significant amount of sliding contact. Hence, the operational noise of a radially compliant scroll is greater than that of a fixed throw scroll.
In a disclosed embodiment of this invention, the scroll compressor has a radially compliant orbiting scroll wrap connected to the driveshaft through a slider block. However, structure is also incorporated into the connection to limit or dampen movement of the orbiting scroll relative to the non-orbiting scroll. It can also limit or eliminate the centrifugal force acting between the two scroll wraps. In a first embodiment, a damper piston extends from an eccentric drive pin on the shaft into contact with the inner bore of the slider block. The piston will resist the force from the centrifugal force tending to move the orbiting scroll into contact with the non-orbiting scroll. Thus, the damper piston, which is spring biased outwardly of the eccentric pin, acts in conjunction with a flank contact force to resist the centrifugal force. In this way, flank contact force is minimized. However, the goal of maintaining the scroll wrap flanks in close proximity to each other is achieved. The spring force should be designed to achieve a maximum orbit, with minimal flank contact during most of that orbit.
In a second embodiment, a normally flat drive surface between the eccentric pin and the inner bore of the slider block has a number of incremental positioning structures. As an example, saw-tooth shapes can be formed on the two surfaces. The relative position of the slider block and the eccentric pin indexes along the incremental surfaces such that a large contact force between the flanks will cause movement of the slider block relative to the pin through the positioning structures to allow the orbiting scroll to move away from the non-orbiting scroll. On the other hand, the incremental positioning surfaces also allow the position of the slider block to advance along the eccentric pin until a balanced position is reached for the particular scroll arrangement. In a sense, the structure will then approximate a fixed throw scroll compressor that is ideally designed for the particular manufacturing tolerances of the components in that scroll compressor.
In general, the application could be described as a scroll compressor having a relationship between a slider block and an eccentric pin wherein the two are structured to allow movement of the slider block relative to the pin, but to limit such movement during operation.
These and other features of the present invention can be best understood from the following specification and drawings. The following of which is a brief description.